Netrin receptors

ABSTRACT

The invention provides methods and compositions relating to vertebrate UNC-5 proteins which function as receptor proteins for netrins, a family of cell guidance proteins. The proteins may be produced recombinantly from transformed host cells from the disclosed vertebrate UNC-5 encoding nucleic acid or purified from human cells. The invention provides specific hybridization probes and primers capable of specifically hybridizing with the disclosed vertebrate unc-5 gene, vertebrate UNC-5-specific binding agents such as specific antibodies, and methods of making and using the subject compositions in diagnosis, therapy and in the biopharmaceutical industry.

This is a divisional application of USSN 08/808,982, filed Feb. 19, 1997, now U.S. Pat. No. 5,939,271 which is incorporated herein by reference.

The research carried out in the subject application was supported in part by grants from the National Institutes of Health. The government may have rights in any patent issuing on this application.

FILED OF THE INVENTION

The field of this invention is proteins which regulate vertebrate cell guidance.

BACKGROUND

In the developing nervous system, migrating cells and axons are guided to their targets by cues in the extracellular environment. The netrins are a family of phylogenetically-conserved guidance cues that can function as diffusible attractants and repellents for different classes of cells and axons¹⁻¹⁰. Recent studies in vertebrates, insects and nematodes have implicated members of the DCC subfamily of the immunoglobulin (Ig) superfamily as receptors involved in migrations toward netrin sources ^(6, 11-13). The mechanisms that direct migrations away from netrin sources (presumed repulsions) are less well understood. In Caenorhabditis elegans, loss of unc-5 (which encodes the transmembrane protein UNC-5¹⁴) function causes defects in these migrations^(15, 16), and ectopic expression of unc-5 in some neurons can redirect their axons away from a netrin source¹⁷. However, the relationship between UNC-5 and the netrins has not been defined. We disclose herein vertebrate homologues of the C. elegans UNC-5, which define a novel subfamily of the Ig superfamnily, and whose mRNAs show prominent expression in various classes of differentiating neurons and we disclose that these vertebrate UNC-5 homologues are vertebrate netrin-binding proteins.

SUMMARY OF THE INVENTION

The invention provides methods and compositions relating to vertebrate UNC-5 proteins, related nucleic acids, and protein domains thereof having vertebrate UNC-5-specific activity. The proteins may be produced recombinantly from transfected host cells from the subject vertebrate UNC-5 encoding nucleic acids or purified from vertebrate cells. The invention provides isolated vertebrate unc-5 hybridization probes and primers capable of specifically hybridizing with the disclosed vertebrate unc-5 genes, vertebrate UNC-5-specific binding agents such as specific antibodies, and methods of making and using the subject compositions in diagnosis (e.g. genetic hybridization screens for vertebrate unc-5 transcripts), therapy (e.g. gene therapy to modulate vertebrate unc-5 gene expression) and in the biopharmaceutical industry (e.g. as immunogens, reagents for modulating cell guidance, reagents for screening chemical libraries for lead pharmacological agents, etc.).

DETAILED DESCRIPTION OF THE INVENTION

The nucleotide sequences of natural unc5h-1 cDNAs from rat and human are shown as SEQ ID NOS:1 and 2, respectively; and the conceptual translates are shown as SEQ ID NOS:5 and 6, respectively. The nucleotide sequences of natural unc5h-2 cDNAs from rat and human are shown as SEQ ID NOS:3 and 4, respectively; and the conceptual translates are shown as SEQ ID NOS:7 and 8, respectively. The vertebrate UNC-5 proteins of the invention include incomplete translates of SEQ ID NOS:1, 2, 3 and 4 and deletion mutants of SEQ ID NOS:5, 6, 7 and 8, which translates and deletion mutants have vertebrate UNC-5-specific amino acid sequence and assay-discernable vertebrate UNC-5-specific binding specificity or function. Such active vertebrate UNC-5 deletion mutants, vertebrate UNC-5 peptides or protein domains comprise at least about 8, preferably at least about 12, more preferably at least about 24 consecutive residues of SEQ ID NO:5, 6, 7 or 8. For examples, vertebrate UNC-5 protein domains identified below are shown to provide protein-binding domains which are identified in and find use, inter alia, in solid-phase binding assays as described below.

Vertebrate UNC-5-specific activity or function may be determined by convenient in vitro, cell-based, or in vivo assays: e.g. in vitro binding assays, cell culture assays, in animals (e.g. gene therapy, transgenics, etc.), etc. Binding assays encompass any assay where the molecular interaction of a vertebrate UNC-5 protein with a binding target is evaluated. The binding target may be a natural extracellular binding target such as a netrin protein, or other regulator that directly modulates vertebrate UNC-5 activity or its localization; or non-natural binding target such a specific immune protein such as an antibody, or an vertebrate UNC-5 specific agent such as those identified in screening assays such as described below. Vertebrate UNC-5-binding specificity may assayed by binding equilibrium constants (usually at least about 10⁷ M⁻¹, preferably at least about 10⁸ M⁻¹, more preferably at least about 10⁹ M⁻¹), by the ability of the subject protein to function as negative mutants in vertebrate UNC-5-expressing cells, to elicit vertebrate UNC-5 specific antibody in a heterologous mammalian host (e.g. a rodent or rabbit), etc. In any event, the vertebrate UNC-5 binding specificity of the subject vertebrate UNC-5 proteins necessarily distinguishes C. elegans UNC-5.

The claimed vertebrate UNC-5 proteins are isolated or pure: an “isolated” protein is unaccompanied by at least some of the material with which it is associated in its natural state, preferably constituting at least about 0.5%, and more preferably at least about 5% by weight of the total protein in a given sample and a pure protein constitutes at least about 90%, and preferably at least about 99% by weight of the total protein in a given sample. The vertebrate UNC-5 proteins and protein domains may be synthesized, produced by recombinant technology, or purified from mammalian, preferably human cells. A wide variety of molecular and biochemical methods are available for biochemical synthesis, molecular expression and purification of the subject compositions, see e.g. Molecular Cloning, A Laboratory Manual (Sambrook, et al. Cold Spring Harbor Laboratory), Current Protocols in Molecular Biology (Eds. Ausubel, et al., Greene Publ. Assoc., Wiley-Interscience, NY) or that are otherwise known in the art.

The invention provides natural and non-natural vertebrate UNC-5-specific binding agents, methods of identifying and making such agents, and their use in diagnosis, therapy and pharmaceutical development. For example, vertebrate UNC-5-specific agents are useful in a variety of diagnostic and therapeutic applications. Vertebrate UNC-5-specific binding agents include vertebrate UNC-5-specific ligands, such as netrins, and somatically recombined protein receptors like specific antibodies or T-cell antigen receptors (see, e.g. Harlow and Lane (1988) Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory) and other natural binding agents identified with assays such as one-, two- and three-hybrid screens, non-natural binding agents identified in screens of chemical libraries such as described below, etc. For diagnostic uses, the binding agents are frequently labeled, such as with fluorescent, radioactive, chemiluminescent, or other easily detectable molecules, either conjugated directly to the binding agent or conjugated to a probe specific for the binding agent. Agents of particular interest modulate vertebrate UNC-5 function, e.g. vertebrate UNC-5-dependent cell guidance; for example, isolated cells, whole tissues, or individuals may be treated with a vertebrate UNC-5 binding agent to activate, inhibit, or alter vertebrate UNC-5-dependent cell guidance or function.

The invention provides UNC-5 related nucleic acids, which find a wide variety of applications including use as translatable transcripts, hybridization probes, PCR primers, diagnostic nucleic acids, etc.; use in detecting the presence of unc-5 genes and gene transcripts and in detecting or amplifying nucleic acids encoding additional unc-5 homologs and UNC-5 structural analogs. The subject nucleic acids are of synthetic/non-natural sequences and/or are isolated, i.e. unaccompanied by at least some of the material with which it is associated in its natural state, preferably constituting at least about 0.5%, preferably at least about 5% by weight of total nucleic acid present in a given fraction, and usually recombinant, meaning they comprise a non-natural sequence or a natural sequence joined to nucleotide(s) other than that which it is joined to on a natural chromosome. Nucleic acids comprising the nucleotide sequence of SEQ ID NO:1, 2, 3 or 4 or fragments thereof, contain such sequence or fragment at a terminus, immediately flanked by a sequence other than that which it is joined to on a natural chromosome, or flanked by a native flanking region fewer than 10 kb, preferably fewer than 2 kb, which is at a terminus or is immediately flanked by a sequence other than that which it is joined to on a natural chromosome. While the nucleic acids are usually RNA or DNA, it is often advantageous to use nucleic acids comprising other bases or nucleotide analogs to provide modified stability, etc.

The amino acid sequences of the disclosed vertebrate UNC-5 proteins are used to back-translate vertebrate UNC-protein-encoding nucleic acids optimized for selected expression systems (Holler et al. (1993) Gene 136, 323-328; Martin et al. (1995) Gene 154, 150-166) or used to generate degenerate oligonucleotide primers and probes for use in the isolation of natural vertebrate UNC-5-encoding nucleic acid sequences (“GCG” software, Genetics Computer Group, Inc, Madison Wis.). vertebrate UNC-5-encoding nucleic acids used in vertebrate UNC-5-expression vectors and incorporated into recombinant host cells, e.g. for expression and screening, transgenic animals, e.g. for functional studies such as the efficacy of candidate drugs for disease associated with vertebrate UNC-5-modulated transcription, etc.

The invention also provides nucleic acid hybridization probes and replication/amplification primers having a vertebrate UNC-5 cDNA specific sequence contained in SEQ ID NO:1, 2, 3 or 4 and sufficient to effect specific hybridization thereto (i.e. specifically hybridize with the corresponding SEQ ID NO:1, 2, 3 or 4 in the presence of C. elegans unc-5 cDNA). Such primers or probes are at least 12, preferably at least 24, more preferably at least 36 and most preferably at least 96 bases in length. Demonstrating specific hybridization generally requires stringent conditions, for example, hybridizing in a buffer comprising 30% formamide in 5×SSPE (0.18 M NaCl, 0.01 M NaPO₄, pH7.7, 0.001 M EDTA) buffer at a temperature of 42° C. and remaining bound when subject to washing at 42° C. with 0.2×SSPE; preferably hybridizing in a buffer comprising 50% formamide in 5×SSPE buffer at a temperature of 42° C. and remaining bound when subject to washing at 42° C. with 0.2×SSPE buffer at 42° C. vertebrate UNC-5 cDNA homologs can also be distinguished from other protein using alignment algorithms, such as BLASTX (Altschul et al. (1990) Basic Local Alignment Search Tool, J Mol Biol 215,403-410).

Vertebrate unc-5 hybridization probes find use in identifying wild-type and mutant vertebrate unc-5 alleles in clinical and laboratory samples. Mutant alleles are used to generate allele-specific oligonucleotide (ASO) probes for high-throughput clinical diagnoses. Therapeutic vertebrate UNC-5 nucleic acids are used to modulate cellular expression or intracellular concentration or availability of active vertebrate UNC-5. For example, vertebrate UNC-5 nucleic acids are also used to modulate cellular expression or intracellular concentration or availability of active vertebrate UNC-5 protein. Vertebrate UNC-5 inhibitory nucleic acids are typically antisense: single-stranded sequences comprising complements of the disclosed natural vertebrate UNC-5 coding sequences. Antisense modulation of the expression of a given vertebrate UNC-5 protein may employ antisense nucleic acids operably linked to gene regulatory sequences. Cells are transfected with a vector comprising a vertebrate UNC-5 sequence with a promoter sequence oriented such that transcription of the gene yields an antisense transcript capable of binding to endogenous vertebrate UNC-5-encoding mRNA. Transcription of the antisense nucleic acid may be constitutive or inducible and the vector may provide for stable extrachromosomal maintenance or integration. Alternatively, single-stranded antisense nucleic acids that bind to genomic DNA or mRNA encoding a given vertebrate UNC-5 protein may be administered to the target cell, in or temporarily isolated from a host, at a concentration that results in a substantial reduction in expression of the targeted protein. An enhancement in vertebrate UNC-5 expression is effected by introducing into the targeted cell type vertebrate UNC-5 nucleic acids which increase the functional expression of the corresponding gene products. Such nucleic acids may be vertebrate UNC-5 expression vectors, vectors which upregulate the functional expression of an endogenous allele, or replacement vectors for targeted correction of mutant alleles. Techniques for introducing the nucleic acids into viable cells are known in the art and include retroviral-based transfection, viral coat protein-liposome mediated transfection, etc.

The invention provides efficient methods of identifying agents, compounds or lead compounds for agents active at the level of a vertebrate UNC-5 modulatable cellular function. Generally, these screening methods involve assaying for compounds which modulate vertebrate UNC-5 interaction with a natural vertebrate UNC-5 binding target. A wide variety of assays for binding agents are provided including labeled in vitro protein-protein binding assays, immunoassays, cell based assays, animal based assay, etc. Preferred methods are amenable to automated, cost-effective high throughput screening of chemical libraries for lead compounds. Such libraries encompass candidate agents of numerous chemical classes, though typically they are organic compounds; preferably small organic compounds and are obtained from a wide variety of sources including libraries of synthetic or natural compounds. Identified agents find use in the pharmaceutical industries for animal and human trials; for example, the agents may be derivatized and rescreened in in vitro and in vivo assays to optimize activity and minimize toxicity for pharmaceutical development.

In vitro binding assays employ a mixture of components including vertebrate UNC-5 protein, which may be part of a fusion product with another peptide or polypeptide, e.g. a tag for detection or anchoring, etc. The assay mixtures comprise a natural extracellular vertebrate UNC-5 binding target, such as a netrin. While native binding targets may be used, it is frequently preferred to use portions (e.g. peptides) thereof so long as the portion provides binding affinity and avidity to the subject vertebrate UNC-5 protein conveniently measurable in the assay. The assay mixture also comprises a candidate pharmacological agent and typically, a variety of other reagents such as salts, buffers, neutral proteins, e.g. albumin, detergents, protease inhibitors, nuclease inhibitors, antimicrobial agents, etc. The mixture components can be added in any order that provides for the requisite bindings and incubations may be performed at any temperature which facilitates optimal binding. The mixture is then incubated under conditions whereby, but for the presence of the candidate pharmacological agent, the vertebrate UNC-5 protein specifically binds the cellular binding target, portion or analog with a reference binding affinity. Incubation periods are likewise selected for optimal binding but also minimized to facilitate rapid, high-throughput screening.

After incubation, the agent-biased binding between the vertebrate UNC-5 protein and one or more binding targets is detected. A separation step is often initially used to separate bound from unbound components. Separation may be effected by precipitation (e.g. TCA precipitation, immunoprecipitation, etc.), immobilization (e.g. on a solid substrate), etc., followed by washing by, for examples, membrane filtration, gel chromatography (e.g. gel filtration, affinity, etc.). One of the components usually comprises or is coupled to a label. The label may provide for direct detection such as radioactivity, luminescence, optical or electron density, etc. or indirect detection such as an epitope tag, an enzyme, etc. A variety of methods may be used to detect the label depending on the nature of the label and other assay components, e.g. through optical or electron density, radiative emissions, nonradiative energy transfers, etc. or indirectly detected with antibody conjugates, etc. A difference in the binding affinity of the vertebrate UNC-5 protein to the target in the absence of the agent as compared with the binding affinity in the presence of the agent indicates that the agent modulates the binding of the vertebrate UNC-5 protein to the vertebrate UNC-5 binding target. Analogously, in the cell-based transcription assay also described below, a difference in the vertebrate UNC-5 transcriptional induction in the presence and absence of an agent indicates the agent modulates vertebrate UNC-5-induced transcription. A difference, as used herein, is statistically significant and preferably represents at least a 50%, more preferably at least a 90% difference.

The following experimental section and examples are offered by way of illustration and not by way of limitation.

EXPERIMENTAL

cDNAs (SEQ ID NO:1 and 3) encoding two rat homologues of UNC-5, termed UNC5H-1 and UNC5H-2 (SEQ ID NOS:5 and 7, respectively), were isolated from an E18 rat brain cDNA library (see Methods). The predicted proteins show sequence similarity with UNC-5 over their entire lengths, but are more similar to one another (52% identity) than to UNC-5 (28% identity in each case). Like UNC-5¹⁴, both possess two predicted Ig-like domains andtwopredictedthrombospondin type-1 repeats in their extracellular domains, a predicted membrane spanning region, and a large intracellular domain (residues 1-332 of SEQ ID NO:5 and 1-334 of SEQ ID NO:7). The UNC5H proteins also each possess a signal sequence which, curiously, is lacking in UNC-5¹⁴. The predicted topology of the UNC5H proteins in cell membranes was verified using recombinant versions of the proteins expressed in transfected cells and antibodies directed against the extracellular and intracellular domains (see Methods). The cytoplasmic domains of the two UNC5H proteins do not contain obvious signaling motifs, but do possess a small region of homology to Zona Occludens-1 (ZO-1), a protein that localizes to adherens junctions and is implicated in junction formation^(18, 19). ZO-1 contains PDZ-domains^(18, 19), structures implicated in protein clustering²⁰, but the region of homology with UNC-5 homologues corresponds to a unique sequence at the carboxy terminus of ZO-1. The homology between ZO-1 and C. elegans UNC-5 is less pronounced (and is not detected by computer BLAST search), but is nonetheless apparent when all four sequences are aligned.

To determine whether the UNC-5 homologues are candidates for receptors involved in neuronal migration or axon guidance, we first examined the sites of expression of Unc5h-1 and Unc5h-2 by RNA in situ hybridization in rat embryos. Unc5h-1 transcripts are detected at early stages of neural tube development in the ventral spinal cord. At embryonic day 11 (E11), when motoneurons are beginning to differentiate in that region²¹, transcripts are present throughout the ventral spinal cord, excluding the midline floor plate region, but are most intense in the ventricular zone and at the lateral edges. At E12, prominent expression is observed in the motor columns, but also extends more dorsally, and is now becoming excluded from the ventricular zone. This more dorsal expression appears transient, as expression by E13 is confined to postmitotic cells in the ventral spinal cord, apparently including the motoneurons. Unc5h-2 transcripts are not detected at significant levels in the spinal cord until E14, when they are found in the roof plate region. Unc5h-2 transcripts are, however, detected in developing sensory ganglia that flank the spinal cord, at low levels at E12, and at higher levels by E14. The expression of these two genes is thus observed in regions where differentiating neurons are undergoing axonogenesis, consistent with a possible role in this process.

Expression of these genes is also observed at higher axial levels of the nervous system, as well as in non-neural structures. At E13, Unc5h-1 is expressed in the basal plate (ventral neural tube) in the hindbrain and midbrain, in the developing hypothalamus and thalamus, and in the pallidum. Unc5h-2 expression at this stage is detected in the dorsal aspect of the developing optic cup, the nasal pits, apical ridge of the limb bud, urogenital tubercle, and in restricted regions of the midbrain and caudal diencephalon. By E16, Unc5h-1 mRNA is also detected at high levels in the entorhinal cortex and at lower levels throughout the cortex. Unc5h-2 is also detected at this stage at low levels in the cortex, and at high levels in hypertrophic chondrocytes. Expression of the two homologues persists postnatally, with, at postnatal day 10 (P10), continued expression of both at low levels throughout the cortex, expression of both in distinct patterns in the septal area, and high level expression of Unc5h-1 in the developing hippocampus and entorhinal cortex. In addition, a prominent site of postnatal expression of both genes is in the cerebellum. Both are expressed in the inner granule cell layer, and Unc5h-2 is in addition expressed in the inner aspect of the external germinal layer, where granule cell precursors differentiate prior to migrating to their final destination in the inner granule cell layer^(22, 23). Thus, expression of Unc5h-2 in this region is associated with a prominent cell migration event in the developing cerebellum.

Although the expression patterns of the two UNC5H proteins were suggestive of potential roles in cell or axon migration, to obtain more direct evidence implicating them in mediating responses to netrins we tested whether netrin-1 can bind cells expressing these proteins. Transfected monkey kidney COS-1 cells or human embryonic kidney 293 cells expressing either UNC5H-1 or UNC5H-2 showed significant binding of netrin-1 protein above background, as is also observed for transfected cells expressing the netrin receptors DCC and neogenin, but not for transfected cells expressing TAG-1 or L1, two other members of the Ig superfamily¹³. In these experiments, binding was performed in the presence of soluble heparin, which eliminates non-specific binding of netrin-1 to the cells¹³ but does not evidently prevent binding to the UNC5 homologues. To verify, in the case of UNC5H-2, that exogenously added heparin is not required for the interaction, we generated a soluble protein comprising the extracellular domain of UNC5H-2 fused to the constant region (Fc) of a human immunogloblin molecule. This UNC5H-2-Fc fusion protein bound transfected 293 cells expressing netrin-1 (some of which remains associated with the surface of these cells^(3, 10)) in the absence of added heparin but did not show binding to non-transfected cells, nor to cells expressing UNC5H-2 itself, DCC, or neogenin. The UNC5H-2-Fc fusion also did not bind transfected cells expressing F-spondin, an adhesive extracellular matrix protein made by floor plate cells²⁴, or Semaphorin III, a chemorepellent for sensory axons at the stages that Unc5h-2 is expressed in sensory ganglia²⁵. Both of these proteins, like netrin-1, are secreted but partition between cell surfaces and the soluble fraction^(24, 26). Thus, the interaction between netrin-1 and UNC5H-2 appears specific, and does not require heparin nor reflect a generalized interaction with proteins that associate non-specifically with cell surfaces.

The affinity of UNC-5 homologues for netrin-1 was estimated in equilibrium binding experiments using netrin(VIoV)-Fc, a fusion of the amino terminal two-thirds of netrin-1 to the constant portion of human IgG¹³. This netrin-1 derivative is bioactive but, unlike netrin-1, does not aggregate at high concentrations, and it binds DCC with a Kd comparable to that of full length netrin-1¹³. Specific binding of netrin (VIoV)-Fc to each of the three UNC5 homologues showed saturation and the binding curves were fitted to the Hill equation, yielding Kd values of 19±0.8 nM and 3.4±1.0 nM for UNC5H1 and UNC5H2 respectively. These values are comparable to the Kd for the DCC-netrin (VIoV-Fc) interaction (˜5 nM), and are consistent with the effective dose for the axon outgrowth promoting effects of netrin-1^(12, 13).

Establishing the involvement of these vertebrate UNC5H proteins in cell migration and axon guidance will require perturbing their functions in vivo. In the meantime, however, our results are at least consistent with such an involvement, as these homologues are expressed by some populations of cells that are undergoing migrations or extending axons. For example, Unc5h1 is expressed by spinal motoneurons, whose axons are repelled in vitro by floor plate cells²⁷, and whose outgrowth in vitro can be suppressed by netrin-1. It is also expressed in the region of trochlear motoneurons, which can be repelled by netrin-1⁴. Both Unc5h genes are also expressed in the developing cerebellum, which is a site of extensive cell migration.

Although the in vivo functions of the UNC-5 homologues described here remain to be determined, our evidence that vertebrate UNC5H proteins bind netrin-1 provides direct support for the idea that members of this new subfamily of the Ig superfamily are netrin receptors. This idea was first proposed for C. elegans UNC-5, based on the findings that unc-5 is required cell-autonomously for dorsal migrations that require the function of the netrin UNC-6¹⁴, and that ectopic expression of unc-5 in neurons that normally project longitudinally or ventrally can steer their axons dorsally¹⁷. Although consistent with the possibility that UNC-5 is an UNC-6 receptor, these results are also consistent with a role for UNC-5 in modifying the function of a distinct UNC-6 receptor. The possibility of a modifier function was made more plausible by evidence that the DCC homologue UNC-40, which is a putative UNC-6 receptor involved in ventral migrations¹¹, is expressed by axons that project dorsally and is required for those projections^(11, 15, 16), suggesting that UNC-5 might function by switching an attractive netrin receptor (UNC-40) into a repulsive netrin receptor. However, our results suggest that UNC-5 also functions directly as a netrin receptor. A model in which UNC-40 and UNC-5 can form a receptor complex but UNC-5 can also function alone in transducing the UNC-6 netrin signal provides an explanation for the observation that loss of unc-40 function results in a much less severe phenotype for dorsal migrations than do either loss of unc-5 or loss of unc-6 function^(15, 16).

Recent studies have demonstrated a remarkable phylogenetic conservation in function of netrin proteins in guiding axons towards a source of netrin at the midline of the nervous systems of nematodes, flies and vertebrates^(1, 7, 8, 9), as well as a conserved role for members of the DCC subfamily of the Ig superfamily in mediating the axonal responses that underlie those guidance events^(11, 12, 13). The identification of vertebrate homologues of UNC-5, and the evidence that they are netrin-binding proteins, suggests that the signaling mechanisms through which netrins elicit repulsive responses are also conserved.

Isolation of rat UNC-5 homologues, and in situ hybridization. A search of the human expressed sequence tag (EST) databases revealed a small sequence (Genbank accession number R11880) with distant similarity to the carboxy-terminal portion of UNC-5. The corresponding cDNA fragment, amplified by polymerase chain reaction from an embryonic human brain cDNA library (Stratagene), was used to screen the library, resulting in the isolation of a 3.8 kB cDNA clone comprising all but the first 440 nt of the coding region of the human homologue of UNC5H1. Non-overlapping probes from this cDNA were used to screen an E18 rat brain library (gift of S. Nakanishi), leading to isolation of seven partial and one full length UNC5H1 cDNA and one full length UNC5H2 cDNA. Additional screens of E13 rat dorsal and ventral spinal cord libraries resulted in isolation of a second full length UNC5H2 cDNA as well as a nearly full length UNC5H 1 cDNA. Sequencing was performed on a Licor (L4000) automated sequencer as well as by ³³P cycle sequencing. Genbank accession numbers are U87305 and U87306 for rUNC5H1 and rUNC5H2 respectively. RNA in situ hybridization was performed as described¹³. Antibodies, expression constructs and immunohistochemistry. Rabbit polyclonal antisera were raised to a peptide corresponding to a sequence (YLRKNFEQEPLAKE, SEQ ID NO:7, residues 148-161) in the extracellular domain of UNC5H-2 that is almost completely conserved in UNCSH-1 (one amino acid substitution), and to peptides corresponding to unique sequences in the cytoplasmic domains of UNC5H-1 (GEPSPDSWSLRLKKQ, SEQ ID NO:5, residues 580-594) and UNC5H-2 (EARQQDDGDLNSLASA, SEQ ID NO:7, residues 909-924). Antisera were affinity-purified on the respective peptides (Quality Controlled Biochemicals). cDNAs for the various constructs were subcloned into the COS cell expression vector pMT21 and the 293-EBNA cell expression vector pCEP4 (Invitrogen), and transiently transfected into those cells using lipofectatnine. The antiserum to the extracellular peptide can detect both UNC5H proteins expressed in transfected cells without cell permeabilization, whereas the antisera directed against the cytoplasmic domain peptides detected their respective proteins after cell permeabilization. Netrin-1 protein (SEQ ID NO:9) was produced, purified, used and visualized in binding assays as described¹³, except that a monoclonal antibody (9E10)²⁹ directed to a C-termi-nal myc-epitope tag was used to detect recombinant netrin-1, and heparin was used at 1 μg/ml. A 293-EBNA cell line stably expressing the UNC5H-2-Fc fusion was derived and maintained as described^(10, 13). The fuision protein was purified from serum-free medium conditioned for seven days by affinity chromatography on protein A agarose. The 293 cell line expressing netrin-1 was as described¹³. Binding of the UNC5H-2-Fc fusion to this line was visualized using a Cy3-conjugated secondary antibody (Jackson lnmunoresearch) directed against human Fc.

References

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EXAMPLES

1. Protocol for high throughput vertebrate UNC-5 - netrin binding assay.

A. Reagents:

Neutralite Avidin:20 μg/ml in PBS.

Blocking buffer:5% BSA, 0.5% Tween 20 in PBS; 1 hour at room temperature.

Assay Buffer:100 mM KCl, 20 mM HEPES pH 7.6, 1 mM MgCl₂, 1% glycerol, 0.5% NP-40, 50 mM b-mercaptoethanol, 1 mg/ml BSA, cocktail of protease inhibitors.

³³P vertebrate UNC-5 protein 10×stock:10⁻⁸−10⁻⁶ M “cold” vertebrate UNC-5 supplemented with 200,000-250,000 cpm of labeled vertebrate UNC-51 (Beckman counter). Place in the 4° C. microfridge during screening.

Protease inhibitor cocktail (1000×):10 mg Trypsin Inhibitor (BMB # 109894), 10 mg Aprotinin (BMB # 236624), 25 mg Benzamidine (Sigma # B-6506), 25 mg Leupeptin (BMB # 1017128), 10 mg APMSF (BMB # 917575), and 2mM NaVo₃ (Sigma # S-6508) in 10 ml of PBS.

nerin-1: 10⁻⁷ −10⁻⁵M biotinylated netrin-1 in PBS.

B. Preparation of assay plates:

Coat with 120 μl of stock N-Avidin per well overnight at 4° C.

Wash 2 times with 200 μl PBS.

Block with 150 μl of blocking buffer.

Wash 2 times with 200 μl PBS.

C. Assay:

Add 40 μl assay buffer/well.

Add 10 μl compound or extract.

Add 10 μl ³³P-UNC-5 (20-25,000 cpm/0.1-10 pmoles/well=10⁻⁹−10⁻⁷ M final conc).

Shake at 25° C. for 15 minutes.

Incubate additional 45 minutes at 25° C.

Add 40 μM biotinylated netrin-1 (0.1-10 pmoles/40 ul in assay buffer)

Incubate 1 hour at room temperature.

Stop the reaction by washing 4 times with 200 μM PBS.

Add 150 μM scintillation cocktail.

Count in Topcount.

D. Controls for all assays (located on each plate):

a. Non-specific binding

b. Soluble (non-biotinylated netrin-1) at 80% inhibition.

All publications and patent applications cited in this specification are herein incorporated by reference as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

9 3014 base pairs nucleic acid double linear cDNA not provided 1 ATGGCCGTCC GGCCCGGCCT GTGGCCAGTG CTCCTGGGCA TAGTCCTCGC CGCCTGGCTT 60 CGTGGTTCGG GTGCCCAGCA GAGTGCCACG GTGGCCAATC CAGTGCCCGG TGCCAACCCC 120 GACCTGCTGC CCCACTTCCT GGTAGAGCCT GAGGACGTGT ACATTGTCAA GAACAAGCCG 180 GTGTTGTTGG TGTGCAAGGC TGTGCCTGCC ACCCAGATCT TCTTCAAGTG CAATGGGGAA 240 TGGGTCCGCC AGGTCGATCA CGTAATTGAA CGCAGCACCG ACAGCAGCAG CGGATTGCCA 300 ACCATGGAGG TCCGTATCAA CGTATCGAGG CAGCAGGTAG AGAAAGTGTT TGGGCTGGAG 360 GAATACTGGT GCCAGTGTGT GGCATGGAGC TCCTCGGGTA CCACCAAAAG TCAGAAGGCC 420 TACATCCGGA TTGCCTATTT GCGCAAGAAC TTTGAGCAGG AGCCACTGGC CAAGGAAGTG 480 TCACTGGAGC AAGGCATTGT ACTACCTTGT CGCCCCCCAG AAGGAATCCC CCCAGCTGAG 540 GTGGAGTGGC TTCGAAATGA GGACCTCGTG GACCCCTCCC TCGATCCCAA TGTGTACATC 600 ACGCGGGAGC ACAGCCTAGT CGTGCGTCAG GCCCGCCTGG CCGACACGGC CAACTACACC 660 TGTGTGGCCA AGAACATCGT AGCCCGTCGC CGAAGCACCT CTGCAGCGGT CATTGTTTAT 720 GTGAACGGTG GGTGGTCGAC GTGGACTGAG TGGTCCGTCT GCAGCGCCAG CTGTGGGCGT 780 GGCTGGCAGA AACGGAGCCG GAGCTGCACC AACCCGGCAC CTCTCAACGG GGGCGCCTTC 840 TGTGAGGGGC AGAATGTCCA GAAAACAGCC TGCGCCACTC TGTGCCCAGT GGATGGGAGC 900 TGGAGTTCGT GGAGTAAGTG GTCAGCCTGT GGGCTTGACT GCACCCACTG GCGGAGCCGC 960 GAGTGCTCTG ACCCAGCACC CCGCAATGGA GGTGAGGAGT GTCGGGGTGC TGACCTGGAC 1020 ACCCGCAACT GTACCAGTGA CCTCTGCCTG CACACCGCTT CTTGCCCCGA GGACGTGGCT 1080 CTCTACATCG GCCTTGTCGC TGTGGCTGTG TGCCTCTTCT TGCTGTTGCT GGCCCTTGGA 1140 CTCATTTACT GTCGCAAGAA GGAAGGGCTG GACTCCGATG TGGCCGACTC GTCCATCCTC 1200 ACCTCGGGCT TCCAGCCTGT CAGCATCAAG CCCAGCAAAG CAGACAACCC CCACCTGCTC 1260 ACCATCCAGC CAGACCTCAG CACCACCACT ACCACCTACC AGGGCAGTCT ATGTTCGAGG 1320 CAGGATGGAC CCAGCCCCAA GTTCCAGCTC TCTAATGGTC ACCTGCTCAG CCCACTGGGG 1380 AGTGGCCGCC ATACGTTGCA CCACAGCTCA CCCACCTCTG AGGCTGAGGA CTTCGTCTCC 1440 CGCCTCTCCA CCCAAAACTA CTTTCGTTCC CTGCCCCGCG GCACCAGCAA CATGGCCTAC 1500 GGGACCTTCA ACTTCCTCGG GGGCCGGCTG ATGATCCCTA ATACGGGGAT CAGCCTCCTC 1560 ATACCCCCGG ATGCCATCCC CCGAGGAAAG ATCTACGAGA TCTACCTCAC ACTGCACAAG 1620 CCAGAAGACG TGAGGTTGCC CCTAGCTGGC TGTCAGACCC TGCTGAGTCC AGTCGTTAGC 1680 TGTGGGCCCC CAGGAGTCCT GCTCACCCGG CCAGTCATCC TTGCAATGGA CCACTGTGGA 1740 GAGCCCAGCC CTGACAGCTG GAGTCTGCGC CTCAAAAAGC AGTCCTGCGA GGGCAGTTGG 1800 GAGGATGTGC TGCACCTTGG TGAGGAGTCA CCTTCCCACC TCTACTACTG CCAGCTGGAG 1860 GCCGGGGCCT GCTATGTCTT CACGGAGCAG CTGGGCCGCT TTGCCCTGGT AGGAGAGGCC 1920 CTCAGCGTGG CTGCCACCAA GCGCCTCAGG CTCCTTCTGT TTGCTCCCGT GGCCTGTACG 1980 TCCCTTGAGT ACAACATCCG AGTGTACTGC CTACACGACA CCCACGACGC TCTCAAGGAG 2040 GTGGTGCAGC TGGAGAAGCA GCTAGGTGGA CAGCTGATCC AGGAGCCTCG CGTCCTGCAC 2100 TTCAAAGACA GTTACCACAA CCTACGTCTC TCCATCCACG ACGTGCCCAG CTCCCTGTGG 2160 AAGAGCAAGC TACTTGTCAG CTACCAGGAG ATCCCTTTTT ACCACATCTG GAACGGCACC 2220 CAGCAGTATC TGCACTGCAC CTTCACCCTG GAGCGCATCA ACGCCAGCAC CAGCGACCTG 2280 GCCTGCAAGG TGTGGGTGTG GCAGGTGGAG GGAGATGGGC AGAGCTTCAA CATCAACTTC 2340 AACATCACTA AGGACACAAG GTTTGCTGAA TTGTTGGCTC TGGAGAGTGA AGGGGGGGTC 2400 CCAGCCCTGG TGGGCCCCAG TGCCTTCAAG ATCCCCTTCC TCATTCGGCA AAAGATCATC 2460 GCCAGTCTGG ACCCACCCTG CAGCCGGGGC GCCGACTGGA GAACTCTAGC CCAGAAACTT 2520 CACCTGGACA GCCATCTTAG CTTCTTTGCC TCCAAGCCCA GCCCTACAGC CATGATCCTC 2580 AACCTATGGG AGGCACGGCA CTTCCCCAAC GGCAACCTCG GCCAGCTGGC AGCAGCTGTG 2640 GCCGGACTGG GCCAACCAGA TGCTGGCCTC TTCACGGTGT CGGAGGCCGA GTGTTGAGAC 2700 CAGCCAGGCC GGTAATGCCT ACATTCTCAC CAGCTTTGAC ACCTGCCAGG GACAGGCAAA 2760 ACCAGACAGG GGCCCTTCCC CCACACCCGG GGAGAGCTGC TTGGACAGGC CCCCTCCTGG 2820 TGAAGTTGTC CCTCGATGCT GGTCCTTCAG ACCCTGCCCA AACTCCATCC CTCCATGGCC 2880 TGCCCGGCCA GGTTGGTCTA GCCACCTGCT CTCACTCTGC CCTGGTCCCA GGGCCAGAGT 2940 AGACAGTCCT GGAGCCTGGG CTGAGCCTCG CCAGCCCATC TGTGTGTGTG TGTATATGCG 3000 TGTATGCTAC CTCT 3014 1787 base pairs nucleic acid double linear cDNA not provided 2 GCAACTGTAC CAGTGACCTC TGGTACACAC TGCTTCTGGC CCTGAGGACG TGGCCCTCTA 60 TGTGGGCCTC ATCGCCGTGG CCGTCTGCCT GGTCCTGCTG CTGCTTGTCC TCATCCTCGT 120 TTATTGCCGG AAGAAGGAGG GGCTGGACTC AGATGTGGCT GACTCGTCCA TTCTCACCTC 180 AGGCTTCCAG CCCGTCAGCA TCTAAGCCCA GCAAAGCAGA CAACCCCCAT CTGCTCACCA 240 TCCAGCCGGA CCTCAGCACC ACCACCACCA CCTACCAGGG CAGTCTCTGT CCCCGGCAGG 300 ATGGGCCCAG CCCCAAGTTC CAGCTCACCA ATGGGCACCT GCTCAGCCCC CTGGGTGGCG 360 GCCGCCACAC ACTGCACCAC AGCTCTCCCA CCTCTGAGGC CGAGGAGTTC GTCTCCCGCC 420 TCTCCACCCA GAACTACTTC CGCTCCCTGC CCCGAGGCAC CAGCAACATG ACCTATGGGA 480 CCTTCAACTT CCTCGGGGGC CGGCTGATGA TCCCTAATAC AGGAATCAGC CTCCTCATCC 540 CCCCAGATGC CATACCCCGA GGGAAGATCT ATGAGATCTA CCTCACGCTG CACAAGCCGG 600 AAGACGTGAG GTTGCCCCTA GCTGGCTGTC AGACCCTGCT GAGTCCCATC GTTAGCTGTG 660 GACCCCCTGG CGTCCTGCTC ACCCGGCCAG TCATCCTGGC TATGGACCAC TGTGGGGAGC 720 CCAGCCCTGA CAGCTGGAGC CTGGCCCTCA AAAAGCAGTC GTGCGAGGGA GCTGGGAGGA 780 TGTCTGCACC TGGGCGAGGA GGCGCCCTCC CACCTCTACT ACTGCCAGCT GGAGGCCAGT 840 GCCTGCTACG TCTTCACCGA GCAGCTGGGC CGCTTTGCCC TGGTGGGAGA GGCCCTCAGC 900 GTGGCTGCCG CCAAGCGCCT CAAGCTGCTT CTGTTTGCGC CGGTGGCCTG CACCTCCCTC 960 GAGTACAACA TCCGGGTCTA CTGCCTGCAT GACACCCACG ATGCACTCAA GGAGGTGGTG 1020 CAGCTGGAGA AGCAGCTGGG GGGACAGCTG ATCCAGGAGC CACGGGTCCT GCACTTAAGG 1080 ACAGTTACCA CAACCTGCCC TATCATCCAC GATGTGCCCA GCTCCCTGTG GAAGAGTAAG 1140 CTCCTTGTCA GCTACCAGGA GATCCCCTTT TATCACATCT GGAATGGCAC GCAGCGGTAC 1200 TTGCACTGCA CCTTCACCCT GGAGCGTGTC AGCCCCAGCA CTAGTGACCT GGCCTGCAAG 1260 CTGTGGGTGT GGCAGGTGGA GGGCGACGGG CAGAGCTTCA GCATCAACTT CAACATCACC 1320 AAGGACACAA GGTTTGCTGA GCTGCTGGCT CTGGAGAGTG AAGCGGGGGT CCCAGCCCTG 1380 GTGGGCCCCA GTGCCTTCAA GATCCCCTTC CTCATTCGGC AGAAGATAAT TTCCAGCCTG 1440 GACCCACCCT GTAGGCGGGG TGCCGACTGG CGGACTCTGG CCCAGAAACT CCACCTGGAC 1500 AGCCATCTCA GCTTCTTTGC CTCCAAGCCC AGCCCCACAG CCATGATCCT CAACCTGTGG 1560 GAGGCGCGGC ACTTCCCCAA CGGCAACCTC AGCCAGCTGG CTGCAGCAGT GGCTGGGACT 1620 GGCCAGCAGG ACGGTGGCTT CTTTCACAGT GTTCGGAGGC TGAGTGCTGA GGCCGGCCAG 1680 GCGAACACTA CAATTTTACC AGTTTTGGGA ACCCACCAAG GGACAGGCAG AAGCCGGACA 1740 AGGGCTTTTC CCAAAACCGG GGAGAGTTTT TTTGGAAAAG GCCTTTT 1787 2831 base pairs nucleic acid double linear cDNA not provided 3 ATGAGGGCCC GGAGCGGCGG GGCCGCTGCT GTGGCGCTGC TGCTCTGCTG GGATCCGACA 60 CCGAGCTTAG CAGGCATTGA CTCTGGTGCC CAGGGACTCC CAGACTCCTT CCCATCAGCA 120 CCCGCGGAGC AGCTGCCTCA CTTCCTGCTG GAACCAGAGG ATGCCTACAT CGTAAAGAAC 180 AAGCCAGTGG AATTGCACTG CCGAGCCTTC CCTGCCACAC AGATCTACTT CAAGTGTAAT 240 GGCGAGTGGG TTAGCCAGAA AGGCCACGTC ACGCAGGAGA GCCTGGATGA GGCCACAGGC 300 TTGCGAATAC GAGAGGTGCA GATAGAGGTG TCGCGGCAGC AGGTGGAGGA ACTTTTTGGG 360 CTCGAGGACT ACTGGTGTCA GTGCGTGGCC TGGAGCTCTT CGGGAACCAC CAAGAGTCGC 420 CGAGCCTACA TCCGCATTGC CTACTTGCGC AAGAACTTTG ACCAGGAGCC TCTGGCGAAG 480 GAGGTACCCT TGGATCATGA GGTCCTTCTG CAGTGCCGCC CACCAGAGGG AGTGCCTGTG 540 GCTGAGGTGG AATGGCTCAA GAATGAAGAT GTCATCGATC CCGCTCAGGA CACTAACTTC 600 CTGCTCACCA TTGACCACAA CCTCATCATC CGCCAGGCGC GCCTCTCAGA CACAGCCAAC 660 TACACCTGTG TGGCAAAGAA TATTGTGGCC AAGCGCCGGA GCACGACGGC CACAGTCATC 720 GTCTATGTGA ACGGAGGTTG GTCCAGCTGG GCAGAATGGT CACCCTGCTC TAACCGCTGC 780 GGCCGAGGTT GGCAGAAACG TACTAGGACC TGCACCAACC CAGCCCCACT CAATGGAGGT 840 GCCTTCTGCG AGGGACAGGC TTGCCAGAAG ACGGCTTGCA CCACCGTGTG CCCAGTGGAT 900 GGAGCGTGGA CTGAGTGGAG CAAGTGGTCC GCCTGCAGCA CAGAGTGTGC GCACTGGCGC 960 AGCCGCGAGT GCATGGCACC GCCGCCCCAG AACGGAGGCC GTGACTGCAG CGGGACGCTA 1020 CTTGACTCCA AGAACTGCAC CGATGGGCTG TGCGTGCTGA ATCAGAGAAC TCTAAACGAC 1080 CCTAAAAGCC GCCCCCTGGA GCCGTCGGGA GACGTGGCGC TGTATGCGGG CCTCGTGGTG 1140 GCCGTCTTTG TGGTTCTGGC AGTTCTCATG GCTGTAGGAG TGATCGTGTA CCGGAGAAAC 1200 TGCCGGGACT TCGACACGGA CATCACTGAC TCCTCTGCTG CCCTCACTGG TGGTTTCCAC 1260 CCCGTCAACT TCAAGACTGC AAGGCCCAGC AACCCACAGC TCCTGCACCC ATCCGCCCCT 1320 CCGGACCTAA CGGCCAGTGC TGGCATCTAC CGCGGACCTG TGTATGCCCT GCAGGACTCT 1380 GCCGACAAGA TCCCTATGAC TAATTCACCC CTTCTGGATC CCTTGCCCAG CCTCAAGATC 1440 AAGGTCTATG ACTCCAGCAC CATCGGCTCT GGGGCTGGCC TGGCTGATGG AGCCGACCTG 1500 CTGGGTGTCT TACCACCCGG TACATACCCA GGCGATTTCT CCCGGGACAC CCACTTCCTG 1560 CACCTGCGCA GCGCCAGCCT TGGTTCCCAG CACCTCCTGG GCCTCCCTCG AGACCCCAGC 1620 AGCAGTGTCA GTGGCACCTT TGGTTGCCTG GGTGGGAGGC TGACCATTCC CGGCACAGGG 1680 GTCAGCCTGT TGGTACCAAA TGGAGCCATT CCCCAGGGCA AGTTCTATGA CTTGTATCTA 1740 CGTATCAACA AGACTGAAAG CACCCTCCCA CTTTCGGAAG GTTCCCAGAC AGTATTGAGC 1800 CCCTCGGTGA CCTGCGGGCC CACGGGCCTC CTCCTGTGCC GCCCTGTTGT CCTCACTGTG 1860 CCCCACTGTG CTGAAGTCAT TGCCGGAGAC TGGATCTTCC AGCTCAAGAC CCAGGCCCAT 1920 CAGGGCCACT GGGAGGAGGT GGTGACTTTG GATGAGGAGA CTCTGAACAC CCCCTGCTAC 1980 TGCCAGCTAG AGGCTAAATC CTGCCACATC CTGTTGGACC AGCTGGGTAC CTACGTGTTC 2040 ACGGGCGAGT CCTACTCCCG CTCCGCAGTC AAGCGGCTCC AGCTAGCCAT CTTCGCCCCA 2100 GCCCTCTGCA CCTCCCTGGA GTATAGTCTC AGGGTCTACT GTCTGGAGGA CACTCCTGCA 2160 GCACTGAAGG AGGTCCTAGA GCTGGAGAGG ACTCTGGGTG GCTACTTGGT GGAGGAGCCC 2220 AAGACTTTGC TCTTTAAGGA CAGTTACCAC AACCTACGCT CTCCCTCCAT GACATCCCCC 2280 ATGCCCACTG GAGGAGCAAA CTACTGGCCA AGTACCAGGA GATTCCCTTC TACCATGTGT 2340 GGAACGGCAG CCAGAAAGCC CTGCACTGCA CTTTCACCCT GGAGAGACAT AGCCTAGCCT 2400 CCACTGAGTT CACCTGTAAG GTCTGCGTGC GGCAGGTAGA AGGGGAAGGC CAGATTTTCC 2460 AGCTGCACAC CACGCTGGCT GAGACGCCTG CTGGCTCCCT GGATGCACTC TGCTCTGCCC 2520 CTGGCAATGC TGCCACCACA CAGCTGGGAC CCTATGCCTT CAAGATACCA CTGTCCATCC 2580 GCCAGAAGAT CTGCAACAGC CTGGACGCCC CCAACTCACG GGGCAATGAC TGGCGGCTGT 2640 TGGCACAGAA GCTCTCCATG GACCGGTACC TGAACTACTT CGCCACCAAA GCTAGTCCCA 2700 CAGGCGTGAT CTTAGACCTC TGGGAAGCTC GGCAGCAGGA TGATGGGGAC CTCAACAGCC 2760 TGGCCAGTGC CTTGGAGGAG ATGGGCAAGA GTGAGATGCT GGTAGCCATG ACCACTGATG 2820 GCGATTGCTG A 2831 305 base pairs nucleic acid double linear cDNA not provided 4 TGGATGAGGA GACCCTGAAC ACACCCTGCT ACTGCAGCTG GAGCCCAGGG CCTGTACATC 60 CTGCTGGACC AGCTGGGCAC CTACGTTTTC ACGGGCGAGT CCTATTCCCG CTCAGCAGTC 120 AAGCGGCTCC AGCTGGCCGT TTCGCCCCCG CCCTCTGCAC CTCCCTGGAG TACAGCCTCC 180 GGGTCTACTG CCTGGAGGAC ACGCCTGTAG CACTGAAGGA GGTGCTGGAG CTGGAGCGGA 240 CTCTGGGCGG ATACTTGGTG GAGGAGCCGA AACCGCTAAT GTTCAAGGAC AGTTACCACA 300 ACCTT 305 898 amino acids amino acid not relevant not relevant peptide not provided 5 Met Ala Val Arg Pro Gly Leu Trp Pro Val Leu Leu Gly Ile Val Leu 1 5 10 15 Ala Ala Trp Leu Arg Gly Ser Gly Ala Gln Gln Ser Ala Thr Val Ala 20 25 30 Asn Pro Val Pro Gly Ala Asn Pro Asp Leu Leu Pro His Phe Leu Val 35 40 45 Glu Pro Glu Asp Val Tyr Ile Val Lys Asn Lys Pro Val Leu Leu Val 50 55 60 Cys Lys Ala Val Pro Ala Thr Gln Ile Phe Phe Lys Cys Asn Gly Glu 65 70 75 80 Trp Val Arg Gln Val Asp His Val Ile Glu Arg Ser Thr Asp Ser Ser 85 90 95 Ser Gly Leu Pro Thr Met Glu Val Arg Ile Asn Val Ser Arg Gln Gln 100 105 110 Val Glu Lys Val Phe Gly Leu Glu Glu Tyr Trp Cys Gln Cys Val Ala 115 120 125 Trp Ser Ser Ser Gly Thr Thr Lys Ser Gln Lys Ala Tyr Ile Arg Ile 130 135 140 Ala Tyr Leu Arg Lys Asn Phe Glu Gln Glu Pro Leu Ala Lys Glu Val 145 150 155 160 Ser Leu Glu Gln Gly Ile Val Leu Pro Cys Arg Pro Pro Glu Gly Ile 165 170 175 Pro Pro Ala Glu Val Glu Trp Leu Arg Asn Glu Asp Leu Val Asp Pro 180 185 190 Ser Leu Asp Pro Asn Val Tyr Ile Thr Arg Glu His Ser Leu Val Val 195 200 205 Arg Gln Ala Arg Leu Ala Asp Thr Ala Asn Tyr Thr Cys Val Ala Lys 210 215 220 Asn Ile Val Ala Arg Arg Arg Ser Thr Ser Ala Ala Val Ile Val Tyr 225 230 235 240 Val Asn Gly Gly Trp Ser Thr Trp Thr Glu Trp Ser Val Cys Ser Ala 245 250 255 Ser Cys Gly Arg Gly Trp Gln Lys Arg Ser Arg Ser Cys Thr Asn Pro 260 265 270 Ala Pro Leu Asn Gly Gly Ala Phe Cys Glu Gly Gln Asn Val Gln Lys 275 280 285 Thr Ala Cys Ala Thr Leu Cys Pro Val Asp Gly Ser Trp Ser Ser Trp 290 295 300 Ser Lys Trp Ser Ala Cys Gly Leu Asp Cys Thr His Trp Arg Ser Arg 305 310 315 320 Glu Cys Ser Asp Pro Ala Pro Arg Asn Gly Gly Glu Glu Cys Arg Gly 325 330 335 Ala Asp Leu Asp Thr Arg Asn Cys Thr Ser Asp Leu Cys Leu His Thr 340 345 350 Ala Ser Cys Pro Glu Asp Val Ala Leu Tyr Ile Gly Leu Val Ala Val 355 360 365 Ala Val Cys Leu Phe Leu Leu Leu Leu Ala Leu Gly Leu Ile Tyr Cys 370 375 380 Arg Lys Lys Glu Gly Leu Asp Ser Asp Val Ala Asp Ser Ser Ile Leu 385 390 395 400 Thr Ser Gly Phe Gln Pro Val Ser Ile Lys Pro Ser Lys Ala Asp Asn 405 410 415 Pro His Leu Leu Thr Ile Gln Pro Asp Leu Ser Thr Thr Thr Thr Thr 420 425 430 Tyr Gln Gly Ser Leu Cys Ser Arg Gln Asp Gly Pro Ser Pro Lys Phe 435 440 445 Gln Leu Ser Asn Gly His Leu Leu Ser Pro Leu Gly Ser Gly Arg His 450 455 460 Thr Leu His His Ser Ser Pro Thr Ser Glu Ala Glu Asp Phe Val Ser 465 470 475 480 Arg Leu Ser Thr Gln Asn Tyr Phe Arg Ser Leu Pro Arg Gly Thr Ser 485 490 495 Asn Met Ala Tyr Gly Thr Phe Asn Phe Leu Gly Gly Arg Leu Met Ile 500 505 510 Pro Asn Thr Gly Ile Ser Leu Leu Ile Pro Pro Asp Ala Ile Pro Arg 515 520 525 Gly Lys Ile Tyr Glu Ile Tyr Leu Thr Leu His Lys Pro Glu Asp Val 530 535 540 Arg Leu Pro Leu Ala Gly Cys Gln Thr Leu Leu Ser Pro Val Val Ser 545 550 555 560 Cys Gly Pro Pro Gly Val Leu Leu Thr Arg Pro Val Ile Leu Ala Met 565 570 575 Asp His Cys Gly Glu Pro Ser Pro Asp Ser Trp Ser Leu Arg Leu Lys 580 585 590 Lys Gln Ser Cys Glu Gly Ser Trp Glu Asp Val Leu His Leu Gly Glu 595 600 605 Glu Ser Pro Ser His Leu Tyr Tyr Cys Gln Leu Glu Ala Gly Ala Cys 610 615 620 Tyr Val Phe Thr Glu Gln Leu Gly Arg Phe Ala Leu Val Gly Glu Ala 625 630 635 640 Leu Ser Val Ala Ala Thr Lys Arg Leu Arg Leu Leu Leu Phe Ala Pro 645 650 655 Val Ala Cys Thr Ser Leu Glu Tyr Asn Ile Arg Val Tyr Cys Leu His 660 665 670 Asp Thr His Asp Ala Leu Lys Glu Val Val Gln Leu Glu Lys Gln Leu 675 680 685 Gly Gly Gln Leu Ile Gln Glu Pro Arg Val Leu His Phe Lys Asp Ser 690 695 700 Tyr His Asn Leu Arg Leu Ser Ile His Asp Val Pro Ser Ser Leu Trp 705 710 715 720 Lys Ser Lys Leu Leu Val Ser Tyr Gln Glu Ile Pro Phe Tyr His Ile 725 730 735 Trp Asn Gly Thr Gln Gln Tyr Leu His Cys Thr Phe Thr Leu Glu Arg 740 745 750 Ile Asn Ala Ser Thr Ser Asp Leu Ala Cys Lys Val Trp Val Trp Gln 755 760 765 Val Glu Gly Asp Gly Gln Ser Phe Asn Ile Asn Phe Asn Ile Thr Lys 770 775 780 Asp Thr Arg Phe Ala Glu Leu Leu Ala Leu Glu Ser Glu Gly Gly Val 785 790 795 800 Pro Ala Leu Val Gly Pro Ser Ala Phe Lys Ile Pro Phe Leu Ile Arg 805 810 815 Gln Lys Ile Ile Ala Ser Leu Asp Pro Pro Cys Ser Arg Gly Ala Asp 820 825 830 Trp Arg Thr Leu Ala Gln Lys Leu His Leu Asp Ser His Leu Ser Phe 835 840 845 Phe Ala Ser Lys Pro Ser Pro Thr Ala Met Ile Leu Asn Leu Trp Glu 850 855 860 Ala Arg His Phe Pro Asn Gly Asn Leu Gly Gln Leu Ala Ala Ala Val 865 870 875 880 Ala Gly Leu Gly Gln Pro Asp Ala Gly Leu Phe Thr Val Ser Glu Ala 885 890 895 Glu Cys 557 amino acids amino acid not relevant not relevant peptide not provided 6 Asn Cys Thr Ser Asp Leu Xaa Val His Thr Ala Ser Gly Pro Glu Asp 1 5 10 15 Val Ala Leu Tyr Val Gly Leu Ile Ala Val Ala Val Cys Leu Val Leu 20 25 30 Leu Leu Leu Val Leu Ile Leu Val Tyr Cys Arg Lys Lys Glu Gly Leu 35 40 45 Asp Ser Asp Val Ala Asp Ser Ser Ile Leu Thr Ser Gly Phe Gln Pro 50 55 60 Val Ser Ile Lys Pro Ser Lys Ala Asp Asn Pro His Leu Leu Thr Ile 65 70 75 80 Gln Pro Asp Leu Ser Thr Thr Thr Thr Thr Tyr Gln Gly Ser Leu Cys 85 90 95 Pro Arg Gln Asp Gly Pro Ser Pro Lys Phe Gln Leu Thr Asn Gly His 100 105 110 Leu Leu Ser Pro Leu Gly Gly Gly Arg His Thr Leu His His Ser Ser 115 120 125 Pro Thr Ser Glu Ala Glu Glu Phe Val Ser Arg Leu Ser Thr Gln Asn 130 135 140 Tyr Phe Arg Ser Leu Pro Arg Gly Thr Ser Asn Met Thr Tyr Gly Thr 145 150 155 160 Phe Asn Phe Leu Gly Gly Arg Leu Met Ile Pro Asn Thr Gly Ile Ser 165 170 175 Leu Leu Ile Pro Pro Asp Ala Ile Pro Arg Gly Lys Ile Tyr Glu Ile 180 185 190 Tyr Leu Thr Leu His Lys Pro Glu Asp Val Arg Leu Pro Leu Ala Gly 195 200 205 Cys Gln Thr Leu Leu Ser Pro Ile Val Ser Cys Gly Pro Pro Gly Val 210 215 220 Leu Leu Thr Arg Pro Val Ile Leu Ala Met Asp His Cys Gly Glu Pro 225 230 235 240 Ser Pro Asp Ser Trp Ser Leu Ala Leu Lys Lys Gln Ser Cys Glu Gly 245 250 255 Ser Trp Glu Asp Val Leu His Leu Gly Glu Glu Ala Pro Ser His Leu 260 265 270 Tyr Tyr Cys Gln Leu Glu Ala Ser Ala Cys Tyr Val Phe Thr Glu Gln 275 280 285 Leu Gly Arg Phe Ala Leu Val Gly Glu Ala Leu Ser Val Ala Ala Ala 290 295 300 Lys Arg Leu Lys Leu Leu Leu Phe Ala Pro Val Ala Cys Thr Ser Leu 305 310 315 320 Glu Tyr Asn Ile Arg Val Tyr Cys Leu His Asp Thr His Asp Ala Leu 325 330 335 Lys Glu Val Val Gln Leu Glu Lys Gln Leu Gly Gly Gln Leu Ile Gln 340 345 350 Glu Pro Arg Val Leu His Leu Xaa Asp Ser Tyr His Asn Leu Xaa Leu 355 360 365 Ser Xaa His Asp Val Pro Ser Ser Leu Trp Lys Ser Lys Leu Leu Val 370 375 380 Ser Tyr Gln Glu Ile Pro Phe Tyr His Ile Trp Asn Gly Thr Gln Arg 385 390 395 400 Tyr Leu His Cys Thr Phe Thr Leu Glu Arg Val Ser Pro Ser Thr Ser 405 410 415 Asp Leu Ala Cys Lys Leu Trp Val Trp Gln Val Glu Gly Asp Gly Gln 420 425 430 Ser Phe Ser Ile Asn Phe Asn Ile Thr Lys Asp Thr Arg Phe Ala Glu 435 440 445 Leu Leu Ala Leu Glu Ser Glu Ala Gly Val Pro Ala Leu Val Gly Pro 450 455 460 Ser Ala Phe Lys Ile Pro Phe Leu Ile Arg Gln Lys Ile Ile Ser Ser 465 470 475 480 Leu Asp Pro Pro Cys Arg Arg Gly Ala Asp Trp Arg Thr Leu Ala Gln 485 490 495 Lys Leu His Leu Asp Ser His Leu Ser Phe Phe Ala Ser Lys Pro Ser 500 505 510 Pro Thr Ala Met Ile Leu Asn Leu Trp Glu Ala Arg His Phe Pro Asn 515 520 525 Gly Asn Leu Ser Gln Leu Ala Ala Ala Val Ala Gly Thr Xaa Pro Ala 530 535 540 Gly Arg Trp Leu Leu Ser Gln Cys Ser Glu Ala Glu Cys 545 550 555 943 amino acids amino acid not relevant not relevant peptide not provided 7 Met Arg Ala Arg Ser Gly Gly Ala Ala Ala Val Ala Leu Leu Leu Cys 1 5 10 15 Trp Asp Pro Thr Pro Ser Leu Ala Gly Ile Asp Ser Gly Ala Gln Gly 20 25 30 Leu Pro Asp Ser Phe Pro Ser Ala Pro Ala Glu Gln Leu Pro His Phe 35 40 45 Leu Leu Glu Pro Glu Asp Ala Tyr Ile Val Lys Asn Lys Pro Val Glu 50 55 60 Leu His Cys Arg Ala Phe Pro Ala Thr Gln Ile Tyr Phe Lys Cys Asn 65 70 75 80 Gly Glu Trp Val Ser Gln Lys Gly His Val Thr Gln Glu Ser Leu Asp 85 90 95 Glu Ala Thr Gly Leu Arg Ile Arg Glu Val Gln Ile Glu Val Ser Arg 100 105 110 Gln Gln Val Glu Glu Leu Phe Gly Leu Glu Asp Tyr Trp Cys Gln Cys 115 120 125 Val Ala Trp Ser Ser Ser Gly Thr Thr Lys Ser Arg Arg Ala Tyr Ile 130 135 140 Arg Ile Ala Tyr Leu Arg Lys Asn Phe Asp Gln Glu Pro Leu Ala Lys 145 150 155 160 Glu Val Pro Leu Asp His Glu Val Leu Leu Gln Cys Arg Pro Pro Glu 165 170 175 Gly Val Pro Val Ala Glu Val Glu Trp Leu Lys Asn Glu Asp Val Ile 180 185 190 Asp Pro Ala Gln Asp Thr Asn Phe Leu Leu Thr Ile Asp His Asn Leu 195 200 205 Ile Ile Arg Gln Ala Arg Leu Ser Asp Thr Ala Asn Tyr Thr Cys Val 210 215 220 Ala Lys Asn Ile Val Ala Lys Arg Arg Ser Thr Thr Ala Thr Val Ile 225 230 235 240 Val Tyr Val Asn Gly Gly Trp Ser Ser Trp Ala Glu Trp Ser Pro Cys 245 250 255 Ser Asn Arg Cys Gly Arg Gly Trp Gln Lys Arg Thr Arg Thr Cys Thr 260 265 270 Asn Pro Ala Pro Leu Asn Gly Gly Ala Phe Cys Glu Gly Gln Ala Cys 275 280 285 Gln Lys Thr Ala Cys Thr Thr Val Cys Pro Val Asp Gly Ala Trp Thr 290 295 300 Glu Trp Ser Lys Trp Ser Ala Cys Ser Thr Glu Cys Ala His Trp Arg 305 310 315 320 Ser Arg Glu Cys Met Ala Pro Pro Pro Gln Asn Gly Gly Arg Asp Cys 325 330 335 Ser Gly Thr Leu Leu Asp Ser Lys Asn Cys Thr Asp Gly Leu Cys Val 340 345 350 Leu Asn Gln Arg Thr Leu Asn Asp Pro Lys Ser Arg Pro Leu Glu Pro 355 360 365 Ser Gly Asp Val Ala Leu Tyr Ala Gly Leu Val Val Ala Val Phe Val 370 375 380 Val Leu Ala Val Leu Met Ala Val Gly Val Ile Val Tyr Arg Arg Asn 385 390 395 400 Cys Arg Asp Phe Asp Thr Asp Ile Thr Asp Ser Ser Ala Ala Leu Thr 405 410 415 Gly Gly Phe His Pro Val Asn Phe Lys Thr Ala Arg Pro Ser Asn Pro 420 425 430 Gln Leu Leu His Pro Ser Ala Pro Pro Asp Leu Thr Ala Ser Ala Gly 435 440 445 Ile Tyr Arg Gly Pro Val Tyr Ala Leu Gln Asp Ser Ala Asp Lys Ile 450 455 460 Pro Met Thr Asn Ser Pro Leu Leu Asp Pro Leu Pro Ser Leu Lys Ile 465 470 475 480 Lys Val Tyr Asp Ser Ser Thr Ile Gly Ser Gly Ala Gly Leu Ala Asp 485 490 495 Gly Ala Asp Leu Leu Gly Val Leu Pro Pro Gly Thr Tyr Pro Gly Asp 500 505 510 Phe Ser Arg Asp Thr His Phe Leu His Leu Arg Ser Ala Ser Leu Gly 515 520 525 Ser Gln His Leu Leu Gly Leu Pro Arg Asp Pro Ser Ser Ser Val Ser 530 535 540 Gly Thr Phe Gly Cys Leu Gly Gly Arg Leu Thr Ile Pro Gly Thr Gly 545 550 555 560 Val Ser Leu Leu Val Pro Asn Gly Ala Ile Pro Gln Gly Lys Phe Tyr 565 570 575 Asp Leu Tyr Leu Arg Ile Asn Lys Thr Glu Ser Thr Leu Pro Leu Ser 580 585 590 Glu Gly Ser Gln Thr Val Leu Ser Pro Ser Val Thr Cys Gly Pro Thr 595 600 605 Gly Leu Leu Leu Cys Arg Pro Val Val Leu Thr Val Pro His Cys Ala 610 615 620 Glu Val Ile Ala Gly Asp Trp Ile Phe Gln Leu Lys Thr Gln Ala His 625 630 635 640 Gln Gly His Trp Glu Glu Val Val Thr Leu Asp Glu Glu Thr Leu Asn 645 650 655 Thr Pro Cys Tyr Cys Gln Leu Glu Ala Lys Ser Cys His Ile Leu Leu 660 665 670 Asp Gln Leu Gly Thr Tyr Val Phe Thr Gly Glu Ser Tyr Ser Arg Ser 675 680 685 Ala Val Lys Arg Leu Gln Leu Ala Ile Phe Ala Pro Ala Leu Cys Thr 690 695 700 Ser Leu Glu Tyr Ser Leu Arg Val Tyr Cys Leu Glu Asp Thr Pro Ala 705 710 715 720 Ala Leu Lys Glu Val Leu Glu Leu Glu Arg Thr Leu Gly Gly Tyr Leu 725 730 735 Val Glu Glu Pro Lys Thr Leu Leu Phe Lys Asp Ser Tyr His Asn Leu 740 745 750 Arg Leu Ser Leu His Asp Ile Pro His Ala His Trp Arg Ser Lys Leu 755 760 765 Leu Ala Lys Tyr Gln Glu Ile Pro Phe Tyr His Val Trp Asn Gly Ser 770 775 780 Gln Lys Ala Leu His Cys Thr Phe Thr Leu Glu Arg His Ser Leu Ala 785 790 795 800 Ser Thr Glu Phe Thr Cys Lys Val Cys Val Arg Gln Val Glu Gly Glu 805 810 815 Gly Gln Ile Phe Gln Leu His Thr Thr Leu Ala Glu Thr Pro Ala Gly 820 825 830 Ser Leu Asp Ala Leu Cys Ser Ala Pro Gly Asn Ala Ala Thr Thr Gln 835 840 845 Leu Gly Pro Tyr Ala Phe Lys Ile Pro Leu Ser Ile Arg Gln Lys Ile 850 855 860 Cys Asn Ser Leu Asp Ala Pro Asn Ser Arg Gly Asn Asp Trp Arg Leu 865 870 875 880 Leu Ala Gln Lys Leu Ser Met Asp Arg Tyr Leu Asn Tyr Phe Ala Thr 885 890 895 Lys Ala Ser Pro Thr Gly Val Ile Leu Asp Leu Trp Glu Ala Arg Gln 900 905 910 Gln Asp Asp Gly Asp Leu Asn Ser Leu Ala Ser Ala Leu Glu Glu Met 915 920 925 Gly Lys Ser Glu Met Leu Val Ala Met Thr Thr Asp Gly Asp Cys 930 935 940 102 amino acids amino acid not relevant not relevant peptide not provided 8 Asp Glu Glu Thr Leu Asn Thr Pro Cys Tyr Xaa Gln Leu Glu Pro Arg 1 5 10 15 Ala Cys Xaa Ile Leu Leu Asp Gln Leu Gly Thr Tyr Val Phe Thr Gly 20 25 30 Glu Ser Tyr Ser Arg Ser Ala Val Lys Arg Leu Gln Leu Ala Val Phe 35 40 45 Ala Pro Ala Leu Cys Thr Ser Leu Glu Tyr Ser Leu Arg Val Tyr Cys 50 55 60 Leu Glu Asp Thr Pro Val Ala Leu Lys Glu Val Leu Glu Leu Glu Arg 65 70 75 80 Thr Leu Gly Gly Tyr Leu Val Glu Glu Pro Lys Pro Leu Met Phe Lys 85 90 95 Asp Ser Tyr His Asn Leu 100 606 amino acids amino acid not relevant not relevant peptide not provided 9 Met Pro Arg Arg Gly Ala Glu Gly Pro Leu Ala Leu Leu Leu Ala Ala 1 5 10 15 Ala Trp Leu Ala Gln Pro Leu Arg Gly Gly Tyr Pro Gly Leu Asn Met 20 25 30 Phe Ala Val Gln Thr Ala Gln Pro Asp Pro Cys Tyr Asp Glu His Gly 35 40 45 Leu Pro Arg Arg Cys Ile Pro Asp Phe Val Asn Ser Ala Phe Gly Lys 50 55 60 Glu Val Lys Val Ser Ser Thr Cys Gly Lys Pro Pro Ser Arg Tyr Cys 65 70 75 80 Val Val Thr Glu Lys Gly Glu Glu Gln Val Arg Ser Cys His Leu Cys 85 90 95 Asn Ala Ser Asp Pro Lys Arg Ala His Pro Pro Ser Phe Leu Thr Asp 100 105 110 Leu Asn Asn Pro His Asn Leu Thr Cys Trp Gln Ser Asp Ser Tyr Val 115 120 125 Gln Tyr Pro His Asn Val Thr Leu Thr Leu Ser Leu Gly Lys Lys Phe 130 135 140 Glu Val Thr Tyr Val Ser Leu Gln Phe Cys Ser Pro Arg Pro Glu Ser 145 150 155 160 Met Ala Ile Tyr Lys Ser Met Asp Tyr Gly Lys Thr Trp Val Pro Phe 165 170 175 Gln Phe Tyr Ser Thr Gln Cys Arg Lys Met Tyr Asn Lys Pro Ser Arg 180 185 190 Ala Ala Ile Thr Lys Gln Asn Glu Gln Glu Ala Ile Cys Thr Asp Ser 195 200 205 His Thr Asp Val Arg Pro Leu Ser Gly Gly Leu Ile Ala Phe Ser Thr 210 215 220 Leu Asp Gly Arg Pro Thr Ala His Asp Phe Asp Asn Ser Pro Val Leu 225 230 235 240 Gln Asp Trp Val Thr Ala Thr Asp Ile Lys Val Thr Phe Ser Arg Leu 245 250 255 His Thr Phe Gly Asp Glu Asn Glu Asp Asp Ser Glu Leu Ala Arg Asp 260 265 270 Ser Tyr Phe Tyr Ala Val Ser Asp Leu Gln Val Gly Gly Arg Cys Lys 275 280 285 Cys Asn Gly His Ala Ser Arg Cys Val Arg Asp Arg Asp Asp Asn Leu 290 295 300 Val Cys Asp Cys Lys His Asn Thr Ala Gly Pro Glu Cys Asp Arg Cys 305 310 315 320 Lys Pro Phe His Tyr Asp Arg Pro Trp Gln Arg Ala Thr Ala Arg Glu 325 330 335 Ala Asn Glu Cys Val Ala Cys Asn Cys Asn Leu His Ala Arg Arg Cys 340 345 350 Arg Phe Asn Met Glu Leu Tyr Lys Leu Ser Gly Arg Lys Ser Gly Gly 355 360 365 Val Cys Leu Asn Cys Arg His Asn Thr Ala Gly Arg His Cys His Tyr 370 375 380 Cys Lys Glu Gly Phe Tyr Arg Asp Leu Ser Lys Pro Ile Ser His Arg 385 390 395 400 Lys Ala Cys Lys Glu Cys Asp Cys His Pro Val Gly Ala Ala Gly Gln 405 410 415 Thr Cys Asn Gln Thr Thr Gly Gln Cys Pro Cys Lys Asp Gly Val Thr 420 425 430 Gly Ile Thr Cys Asn Arg Cys Ala Lys Gly Tyr Gln Gln Ser Arg Ser 435 440 445 Pro Ile Ala Pro Cys Ile Lys Ile Pro Ala Ala Pro Pro Pro Thr Ala 450 455 460 Ala Ser Ser Thr Glu Glu Pro Ala Asp Cys Asp Ser Tyr Cys Lys Ala 465 470 475 480 Ser Lys Gly Lys Leu Lys Ile Asn Met Lys Lys Tyr Cys Lys Lys Asp 485 490 495 Tyr Ala Val Gln Ile His Ile Leu Lys Ala Glu Lys Asn Ala Asp Trp 500 505 510 Trp Lys Phe Thr Val Asn Ile Ile Ser Val Tyr Lys Gln Gly Ser Asn 515 520 525 Arg Leu Arg Arg Gly Asp Gln Thr Leu Trp Val His Ala Lys Asp Ile 530 535 540 Ala Cys Lys Cys Pro Lys Val Lys Pro Met Lys Lys Tyr Leu Leu Leu 545 550 555 560 Gly Ser Thr Glu Asp Ser Pro Asp Gln Ser Gly Ile Ile Ala Asp Lys 565 570 575 Ser Ser Leu Val Ile Gln Trp Arg Asp Thr Trp Ala Arg Arg Leu Arg 580 585 590 Lys Phe Gln Gln Arg Glu Lys Lys Gly Lys Cys Arg Lys Ala 595 600 605 

What is claimed is:
 1. An isolated polypeptide comprising SEQ ID NO: 5, 6, 7 or 8, or a fragment thereof which is at least eight amino acids in length and elicits an antibody specific to a protein consisting of the corresponding SEQ ID NO:5, 6, 7 or
 8. 2. A polypeptide according to claim 1, comprising SEQ ID NO: 5 or a fragment thereof which is at least eight amino acids in length and elicits an antibody specific to a protein consisting of SEQ ID NO:5.
 3. A polypeptide according to claim 1, comprising SEQ ID NO: 6 or a fragment thereof which is at least eight amino acids in length and elicits an antibody specific to a protein consisting of SEQ ID NO:6.
 4. A polypeptide according to claim 1, comprising SEQ ID NO: 7 or a fragment thereof which is at least eight amino acids in length and elicits an antibody specific to a protein consisting of SEQ ID NO:7.
 5. A polypeptide according to claim 1, comprising SEQ ID NO: 8 or a fragment thereof which is at least eight amino acids in length and elicits an antibody specific to a protein consisting of SEQ ID NO:8.
 6. A polypeptide according to claim 1, wherein the fragment is at least 12 amino acids in length.
 7. A polypeptide according to claim 1, wherein the fragment is at least 24 amino acids in length.
 8. A polypeptide according to claim 1, wherein the fragment comprises residues 148-161 of SEQ ID NO:7.
 9. A polypeptide according to claim 1, wherein the fragment comprises residues 580-594 of SEQ ID NO:5.
 10. A polypeptide according to claim 1, wherein the fragment comprises residues 909-924 of SEQ ID NO:7.
 11. A polypeptide according to claim 1, comprising SEQ ID NO:5 or 7, or a fragment thereof which specifically binds a netrin-1 consisting of the amino acid sequence set forth as SEQ ID NO:9.
 12. A polypeptide according to claim 1, comprising SEQ ID NO:
 5. 13. A polypeptide according to claim 1, comprising SEQ ID NO:
 6. 14. A polypeptide according to claim 1, comprising SEQ ID NO:
 7. 15. A polypeptide according to claim 1, comprising SEQ ID NO:
 8. 16. A method of screening for an agent which modulates the binding of a vertebrate UNC-5 protein to a binding target, said method comprising the steps of: incubating a mixture comprising: a polypeptide according to claim 1, a binding target of said polypeptide and a candidate agent; under conditions whereby, but for the presence of said agent, said polypeptide specifically binds said binding target at a reference affinity; detecting the binding affinity of said polypeptide to said binding target to determine an agent-biased affinity, wherein a difference between the agent-biased affinity and the reference affinity indicates that said agent modulates the binding of said polypeptide to said binding target.
 17. A method according to claim 16, wherein said binding target is a netrin-1 consisting of the amino acid sequence set forth as SEQ ID NO:9 and said polypeptide comprises SEQ ID NO:5 or 7, or a fragment thereof which specifically binds a netrin-1 consisting of the amino acid sequence set forth as SEQ ID NO:9. 